1. Field of the Invention
The present invention relates to a color filter, an image processing apparatus, an image processing method, an image-capture apparatus, an image-capture method, a program and a recording medium, and more particularly, to a color filter, an image processing apparatus, an image processing method, an image-capture apparatus, an image-capture method, a program and a recording medium, which allow to obtain chromatic aberration-cancelled and blur-free images.
2. Description of Related Art
In recent years, digital cameras are widely and commonly used. In the digital cameras, after an image signal, which is obtained using an imaging device (or an image sensor) such as CCDs and CMOSs through a lens, is digitized and then given appropriate image processing, a resultant image signal is recorded in a recording medium such as a flash memory or is directly transferred to an information processing apparatus such as a personal computer by means of cable connections, infrared communications, or the like. With respect to the information processing apparatus such as the personal computers, it is possible to display an image corresponding to the supplied image signal on a monitor such as CRTs (Cathode Ray Tubes) and liquid crystal displays.
An image sensor of a typical type widely used in related art is equipped with three types of color filters, R (red), G (green) and B (blue). Specifically, each pixel of the image sensor is configured for receiving only one of R (red), G (green) and B (blue) wavelength components. In other words, the image signal obtained using the image sensor includes a pixel group capable of acquiring a R (red) spectral component, a pixel group capable of acquiring a G (green) spectral component and a pixel group capable of acquiring a B (blue) spectral component. An example of color arrangement used in the color filter is shown in FIG. 1, being referred to as Bayer array.
If such an image-capture processing using the image sensor is to perform and a subject to be image-captured is in low brightness, i.e. the light amount obtained from the subject is insufficient, an output from the image sensor becomes small, and a resultant image signal is buried under noise, whereby the final output image also becomes an image containing much noise.
Accordingly, in the related art, a signal processing technology is used, which provides an image of high resolution using an imaging device having the color array shown in FIG. 2, or the Bayer array combining Y (white) serving as a luminance signal and R (red), G (green) and B (blue) (See Japanese Patent Application Publication Hei 04-88784, for instance). According to the technology of this type, assuming that Y pixels are arrayed in mosaic form as shown in FIG. 2 in a color filter array and that all the pixels are insensitive to infrared light, it is possible to achieve high resolution using the Y pixels included in pixels arrayed in mosaic form.
Specifically, according to the color filter array shown in FIG. 2, the Y pixels arrayed in mosaic form are sensitive to the substantially whole visible light, so that it is possible to obtain an image signal of higher intensity with respect to the same subject, as compared with the color filter array whose G (green) pixels are arrayed in mosaic form as shown in FIG. 1. For that reason, the use of the color filter shown in FIG. 2 may increase S/N ratio of a signal that corresponds to the mosaic arrangement and controls the resolution, as compared with the use of the color filter whose G (green) pixels are arrayed in mosaic form as shown in FIG. 1.